What should I expect ?

Discussion in 'Pumps and Tanks Well Forum & Blog' started by david u, Oct 12, 2010.

  1. david u

    david u New Member

    Messages:
    13
    Location:
    north texas
    First time poster here. I am having a new well drilled next week and hope for some good advise. This well will be for irrigating a bunch of young pecan trees. The well guy has dug other wells in the area and believes he'll hit "good" water at 200'. Also will be a 4" pipe and 1 1/2HP pump. He also thinks it will be about a 10 GPM well. So after some research, I think I would like to use a Cycle
    Stop Valve and a smaller pressure tank. What should I expect as far as what the well driller will provide on this job? He has quoted a price/ft for drilling and then a ball-park for every thing else. Example $17/ft then quoted about $6000.00 for the total job. What does the "total job" usually mean? I am in a rural(no inspection) area. I also would like to use a Franklin motor based on what I have read. Is it unreasonable to ask for these things when I have the well dug? du
  2. ncgeo

    ncgeo In the Trades

    Messages:
    47
    Location:
    North Carolina
    This doesn't answer your question but assuming the well production is sufficient you should size the pump based on your actual water need and not what is typical in the area. The fact that you are considering a CSV would indicate you will not always be using the maximum pump output (estimated 10 GPM at 200'). If you were using the full output you would not need the CSV. So you might consider a smaller pump, unless you truly need that 10 GPM at times.

    If your installing new irrigation you have some additionally flexibility here, by sizing the irrigation system to match the pump output.

    Do your homework (i.e. read the pump curves) with regard to the pump selection ... my personal experience with this is a prominent driller/pump installer in the area suggested a 1-1/2 HP pump when he heard my well was to be used for a geothermal heat pump. Instead I installed a 1/2 HP pump, and probably could have gone with a 1/3. An extreme example for sure, but it shows what could happen when a pump is spec'd with no regard to actual water need.
  3. ncgeo

    ncgeo In the Trades

    Messages:
    47
    Location:
    North Carolina
    Actually that should read "what could happen when a pump is spec'd with no regard to pumping depth" ... motor power is more related to pumping height/pressure than volume.
  4. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    We may assume you will be drip irrigating at 8 to 9 GPM based on your well at 10 GPM. We do not know if the water is at 200 feet or if the well is 200' with the water sitting at 50'.

    I would say 1.5 hp is massive overkill, especially if you use a CSV which will keep the pump running if you use 1 gpm or 15 gpm. Size a pump for your pressure/ flow required by the irrigation design, i.e. the smallest possible HP to do the job.

    If you cant figure it, post all your parameters here and you will get some suggestions for a pump HP and stages.
  5. david u

    david u New Member

    Messages:
    13
    Location:
    north texas
    Thanks for reply. I don't know the static water level yet. The immature trees will only need about 1 GPM starting off using 1 GPH emitters, but later the well output will not meet all the trees water needs. So, then the pump will have to run continuously for may hours every day..du
  6. justwater

    justwater Well Drilling/Service

    Messages:
    327
    Location:
    FL/GA
    after reading your post and how much water you'll eventually need, personally, i would probably get the biggest pump the well would allow.. it wont matter with the csv. when you need more volume, its there. no tedious measuring and adjusting to keep from excessive cycling. the constant pressure truly shines with irrigation systems.

    btw, no its not unreasonable to ask a well man about a preferred pump. after all, you are the one paying. worst he can say is that he doesnt use them, but cant imagine someone being unwilling to use a franklin.
    Last edited: Oct 12, 2010
  7. Thatguy

    Thatguy Homeowner

    Messages:
    1,459
    Location:
    MD
    Oversized pump = low pumping efficiency, so you pay more for the elec. to run the pump, maybe up to 5x more, and you pay more for the pump.
    I guess if a pump is slightly undersized it can be remedied with a booster pump of some kind.
    Last edited: Oct 13, 2010
  8. david u

    david u New Member

    Messages:
    13
    Location:
    north texas
    Thanks for the replys. I am probably putting the cart in front of the horse. I'll just wait until the well is drilled. Then I'll know more , come back here with some useful info & get the resident experts' opinion. I always value an unbiased, knowledgeable source more than a sellers..du
  9. justwater

    justwater Well Drilling/Service

    Messages:
    327
    Location:
    FL/GA
    i use csv on personal system and change my well pump like i change my underwear. 1/2hp-1.5hp.. and havent seen any notable differences in my power bill.

    though i've never amp tested it to be certain, i would guess that when using the cycle stop valve, a 20 gpm pump moving 10gpm will pull similar numbers to a 10gpm pump at full flow. am i off my rocker here?

    if eventually he is planning on maxing out whatever pump he buys, i would have a tough time calling any pump "oversized". initial pump price differences are small compared to pulling it all out later and replacing when unhappy with undersized irrigation pump... rarely hear a customer complain of too much water, but have def. heard a few complain about not enough, especially on irrigation systems. jmo.
  10. valveman

    valveman Moderator Staff Member

    Messages:
    4,549
    Location:
    Lubbock, Texas
    A 1 HP pump can deliver 10 GPM from 200’ at 40 PSI. If you choose the right pump, a CSV will make it drop to a little over ½ HP load when only pumping 1 GPM. Any pump is more efficient at higher flow rates. If you can use 5 gph emitters instead of 1 gph, you would get across faster and more efficiently. I don’t think starting with a smaller pump will ever save enough energy to pay for a larger pump to be installed when it is needed.

    I have worked on several pecan orchards over the years. They usually start out with drip systems. As the trees get larger they switch to sprinklers. As the trees get even larger, I have seen them remove and sell every other tree, to give more room for the remaining trees.

    The CSV will give you the flexibility to irrigate anyway you want. Flexibility in irrigation maybe a little less efficient electrically at low flow but, can really conserve water and can be better for the trees.
  11. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    I only change my pumps each 10 to 20 years, so that underwear must stand up on its own at night!
  12. david u

    david u New Member

    Messages:
    13
    Location:
    north texas
    Thanks for the replys[​IMG] First attempt at image download. Hope it's image code needed. This is diagram of what I would like to do in the well house. Would like critique of layout
  13. justwater

    justwater Well Drilling/Service

    Messages:
    327
    Location:
    FL/GA
    Lol, nice! To clarify, my personal pumps are just part pumps that I have little to no money in. Every now and then I'll get a buddy that wants a pump on the cheap, so I'll give him mine (been using it and know it's good) for a small fee and put on another part pump. these are jet pumps of course fed by an artesian well with natural pressure. Most of our submersible systems include CSV though.

    As for the picture, after the CSV and switch, A typical irrigation system around here would have 2 lines with cutoff on each line.. One irrig, one all other... that's it. I don't know much about tree farming though (injection? Will u be running chemicals through irrigation as well?) so maybe u need all the other stuff.. wish i could help more there.
    Last edited: Oct 13, 2010
  14. david u

    david u New Member

    Messages:
    13
    Location:
    north texas
    justwater, with drip irrigation you have to be able to inject either chlorine for algae or acid for Ca+ buildup. Since I have to use emitters @1-2 GPH. it's pretty easy for them to clog up. If I had more anticipated water flow than 10 GPM, then I would use micro sprinklers. I hope someone here has knowledge of both well & irrigation to keep my plans on course...du
  15. Thatguy

    Thatguy Homeowner

    Messages:
    1,459
    Location:
    MD
    Last edited: Oct 13, 2010
  16. justwater

    justwater Well Drilling/Service

    Messages:
    327
    Location:
    FL/GA
    that makes sense, I'm not familiar with that. May be dumb question but If u zone it correctly couldn't u use microsprinklers with whatever gpm the well produces? looks like u have a good handle on this, but I have no doubt others here can help u out.
  17. david u

    david u New Member

    Messages:
    13
    Location:
    north texas
    If this were a typical layout, then additional zones would be more feasible
    [​IMG] But I am planting trees along a creek in random areas over large distances. That's why I am using a irrigation designer to size the pipe and do a take off...du Thatguy, thanks for the links. I have read everything on the second link, but the first is a new one.. thanks again..du
    Last edited: Oct 13, 2010
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